Platinum compound

ABSTRACT

The present invention relates to a platinum compound having the formula ##STR1## wherein R represents hydrogen atom, an alkali metal atom or a lower alkyl group. The platinum compound is effective as an antitumor and antimicrobial drug.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to a platinum compound having the formula##STR2## wherein R represents hydrogen atom, an alkali metal atom or alower alkyl group and a drug comprising the same.

2. Description of the Prior Arts

Antitumor effects of platinum compounds have been studied to expectclinical applications. For example, cis-[diamine dichloroplatinum (II)](hereinafter referring to as cis-ddp) has been proposed. The cis-ddp iswater insoluble and had kidney toxicity and accordingly, theadministration is limited. Various studies for overcoming thedisadvantage have been made as disclosed in J. NATL. CANCER Inst. 57841-845 (1976); Gann 69, 263-265 (1978). It has not been satisfactory toimpart water solubility and to reduce kidney toxicity.

Various studies have been made to overcome these disadvantages.

SUMMARY OF THE INVENTION

It is an object of the present invention to provide novel platinumcompounds having antimicrobial effects and antitumor effects.

The novel platinum compounds of the present invention are compoundshaving the formula ##STR3## wherein R represents hydrogen atom, analkali metal atom or a lower alkyl group.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

According to various studies for overcoming the disadvantages of theknown platinum compounds, it has been found that platinum complexeshaving an amino acid derivative as ligand are effective. The presentinvention has been attained by the finding.

The novel platinum compound has a dimer of glycine as a ligand and oneor two carboxyl groups thereof are converted into the ester or salt formto increase the solubility to water and to reduce the side-effect.

In the formula (1), R represents hydrogen atom, an alkali metal atom ora lower alkyl group. The lower alkyl group is methyl, ethy or propylgroup and the alkali metal atom is sodium, potassium or lithium atom.

The process for producing the platinum compounds in this invention willbe illustrated. A compound having the formula (2) ##STR4## wherein R andR₁ respectively represent a lower alkyl group of methy, ethyl or propylgroup (the known compound described in JCS: chem. comm. 238 (1977)) wasdissolved in an alcohol such as methanol and ethanol and an acid such ashydrochloric acid and sulfuric acid is added to said solution to reactthem for 0.5 to 10 hours preferably 1 to 5 hours under refluxing. Then,the reaction mixture is concentrated under a reduced pressure and theproduct is recrystallyzed from an organic solvent such as a mixedsolvent of methanol, ethanol, propanol, n-hexane and dioxane to obtain acompound (3). ##STR5## wherein R is defined in the formula (2). Then,the compound (3) is dissolved into water. A solution of achloroplatinoate in water and a hydrogencarbonate are added to thesolution of the compound (3).

The chloroplatinoate is sodium or potassium salt and thehydrogencarbonate is sodium, potassium, calcium or magnesium salt.

The reaction is performed at room temperature for 5 minutes to 3 hoursand a precipitate is separated and dissolved into water andrecrystallized. The resulting compound has the formula (4). ##STR6##wherein R is defined in the formula (2).

The compound (4) is dispersed and dissolved in water and a metalhydroxide such as sodium or potassium hydroxide is added at an equimoleand the mixture is heated at 60° to 100° C. for 10 to 180 minutes toreact them. A water soluble organic solvent such as acetone, dioxane andDMSO is added to the reaction mixture to obtain a precipitate. Theresulting precipitate is sodium or potassium salt as the compound of thepresent invention.

The free carboxylic acid thereof can be obtained by adding an acidicaqueous solution such as an aqueous solution of hydrochloric acid (pH: 1to 4).

The characteristics of the resulting compounds are shown in Table 1.

                  TABLE 1                                                         ______________________________________                                                                Melting     Solubility                                No.  Compound           point (°C.)                                                                        to water                                  ______________________________________                                              ##STR7##          decomposition at about 253° C.                                                     Δ                                   2                                                                                   ##STR8##          decomposition at about 250° C.                                                     ○                                  3                                                                                   ##STR9##          brown coloring at about 265° C.                                                    ⊚                          4                                                                                   ##STR10##         brown coloring at about 270° C.                                                    ⊚                          5                                                                                   ##STR11##         trans-salt for- mation at 275° C.                                      decomposi- tion at 340° C.                                                         X                                         ______________________________________                                        Elementary analysis                                                           C, H, N                                                                       (calculated value)                                                            No.     C (%)   H (%)       N (%) Note                                        ______________________________________                                        1       16.30   2.60        6.20  Invention                                           (16.29  2.73        6.33)                                             2       11.40   1.85        6.66  "                                                   (11.59  1.94        6.75)                                             3       10.45   1.31        6.10  "                                                   (10.53  1.32        6.13)                                             4       9.90    1.30        5.75  "                                                   (9.79   1.23        5.70)                                             5                                 Reference                                   ______________________________________                                         Note:                                                                         ⊚ remarkably soluble                                           ○ soluble                                                              Δ soluble at high temperature                                           X insoluble                                                              

The acute toxicity of the compounds of the present invention will beillustrated.

Acute toxicity of the compounds is studied by an administration by routeof intraperitoneal injection for ICR-JCL mice.

A solution of the compound in a physiological saline solution isadministered to the mice and the toxicity is observed after theadministration to study mortal number for 7 days and lethal dosage(LD₅₀) is measured by Litchfield-Wilcoxon graph method.

LD₅₀ of Compound No. 5 as the reference compound is 50 mg./kg. whereasLD₅₀ of Compounds Nos. 1 to 4 as the compounds of the invention is morethan 130 mg./kg. The lower toxicity of the compounds of the presentinvention is found. The compounds of the present invention haveantimicrobial effects and antitumor effects. The compounds of thepresent invention are effective for various tumors such as sacroma 180,P-388 leukemia, L-1210 leukemia, Ehrlich cancer, Yoshida sacroma, andovarian tumor, prostatic tumor, laryngeal tumor, vesical tumor, breasttumor and endometritis tumor. The compounds of the invention haveantimicrobial effects to gram's stain negative bacillius such ascoliform bacillius and are effective for remedy from infection andespecially effective as antimicrobial drug.

The drug is administered as a desired composition for oral or parenteraladministration. The formulations of the drug compositions can be tablet,sugar coated tablet, pill, capsule, powder, granule, troche, liquid,suppository and injection. The drug is prepared by admixing the compoundwith a pharmacologically acceptable carrier. Suitable carriers includesugar, glucose, sorbitol, mannitol, potatostarch, cornstarch,amylopectin, and other starches; cellulose derivatives such ascarboxymethyl cellulose, hydroxypropyl cellulose; gelatin, magnesiumstearate, polyvinyl alcohol, calcium stearate, polyethyleneglycol,arabic gum, talc, titanium dioxide; vegetable oils such as olive oil,peanut oil and sesame oil; paraffin oil, neutral fats, ethanol, normalsaline solution, sterilized water, glycerin, coloring agents,seasonings, thickners, stabilizers, surfactants and buffers and otherpharmacologically acceptable carriers. The drug may comprises 0.001 to85 wt.% especially 0.005 to 60 wt.% of the compound of the invention.The dose of the compound of the invention is ranging from 0.005 to 100mg. preferably 0.01 to 50 mg./kg./day/adult depending upon thecondition.

The present invention will be further illustrated by certain examplesand references which are provided for purposes of illustration only.

EXAMPLE 1

Into 80 ml. of methanol, 2,000 mg. of dimer of methyl ester of N-acetylglycine was dissolved and about 1 ml. of hydrochloric acid was added andthe mixture was refluxed for 3 hours.

After the reaction, the reaction mixture was concentrated under areduced pressure and the product was recrystallized from a mixture ofethanol and n-hexane to obtain 1.5 g of the compound having the formula(3) wherein R is methyl group. The yield was 78%. The product had amelting point of 158° to 159° C. and the following elementary analysis.

    ______________________________________                                                C (%)       H (%)   N (%)                                             ______________________________________                                        Calculated:                                                                             28.92         5.65    11.23                                         Found:    29.10         5.60    11.00                                         ______________________________________                                    

The product was soluble in water, methanol and ethanol and insoluble inbenzene and chloroform. The Infrared spectrum is shown in Table 6-1.

EXAMPLE 2

Into 1 ml. of water, 400 mg. of the compound obtained by Example 1 wasdissolved and a solution of 540 mg. of potassium chloroplatinoate in 2ml. of water was added and 108 mg. of NaHCO₃ as powder was graduallyadded. The precipitated crystal was separated and recrystallized fromwater to obtain 4 mg. of powdery crystal. The product was soluble in hotwater of 60° C. and insoluble in organic solvents. The yield was 56%.The product had a melting point of 253° C. (decomposition) and had thefollowing elementary analysis:

    ______________________________________                                                C (%)       H (%)   N (%)                                             ______________________________________                                        Calculated:                                                                             16.29         2.73    6.33                                          Found:    16.30         2.60    6.20                                          ______________________________________                                    

The product had the formula (4) wherein R is methyl group. The infraredspectrum is shown in Table 6-2.

EXAMPLE 3

To 10 ml. of water, 200 mg. of the product of Example 2 and sodiumhydroxide at an equimolar ratio were added and the mixture was stirredat 80° C. for 30 minutes. After cooling the mixture, acetone was addedto separate a precipitate. The precipitate was dried to obtain a powder.The yield was 53%. The product had a melting point of 265° C.(decomposition). The product was soluble in water and insoluble inorganic solvents of benzene and chloroform. The infrared spectrum isshown in Table 6-3. The product had the formula (4) wherein R is Na.

In accordance with the same process except using potassium hydroxideinstead of sodium hydroxide, the product of the present invention as thepotassium salt was obtained. The product had a melting point of 270° C.(decomposition). The yield was 55%. The infrared spectrum is shown inTable 6-4. The product had the formula (4) wherein R is K.

EXAMPLE 4

Into 5 ml. of water, 100 mg. of the product of Example 3 as the sodiumsalt was dissolved and hydrochloric acid was added to give pH of 2 to 3to precipitate the crystal. The yield was 45%. The product had a meltingpoint of 250° C. (decomposition) and was soluble in water. The producthad the formula (4) wherein R is H.

EXAMPLE 5

Antitumor effects of the products to mouse P-388 leukemia were tested.

P-388 ascites cells obtained by a successive cultivation in DBA/2 micewere transplanted by the route of intraperitoneal injection into CDF₁mice (10 mice in one group) at a rate of 1×10⁶ /mouse. From 24 hoursafter the transplantation, a solution of each compound in physiologicalsaline solution was injected once a day for 5 days as 5 times by theroute of intraperitoneal injection. Each average survival days (T) ofthe administered group and each average survival days (C) of controlgroup were measured to calculate each percentage increase in life span(ILS(%))

    ILS(%)=T/C×100

                  TABLE 2                                                         ______________________________________                                                                Dose                                                                          (mg/    ILS                                           No.  Compound           kg)     (%)  Note                                     ______________________________________                                              ##STR12##         5       210  Invention                                2                                                                                   ##STR13##         5       220    "                                      3                                                                                   ##STR14##         5       230    "                                      4                                                                                   ##STR15##         5       225    "                                      5                                                                                   ##STR16##         5       180  Reference (cis-ddp)                      ______________________________________                                    

As it is clear from the results, the compounds of the present inventionimpart higher ILS(%) than that of the reference cis-ddp. Moreover, thesolubilities of the compounds of the present invention to water areincreased to reduce kidney toxicity and other side-effects.

In the group for the administration of cis-ddp, remarkable weightdecrease and kidney cell damage were observed for all of 10 mice. In thegroups of the administration of the compounds of the present invention,slight weight decreases were found during the administration, however,the weight were recovered and kidney cell damages were remarkablyslight.

EXAMPLE 6 Antitumor effect to rabbit V-7 tumor

A solid tumor obtained by transplantation and proliferation to rabbitfemoralis was extracted and cut by scissors in piecies and scievedthrough a stainless steel screen (200 mesh). The tumor cell wastransplanted into thin muscle of rabbit femoralis by the route of aninjection at a rate of about 1.5×10⁷ cells/0.4 ml. Each compound wasadministered for 2 times 7th and 11th day after the transplantation, andaverage survival days were measured with the control group and each lifeprolonging rate was calculated.

                  TABLE 3                                                         ______________________________________                                                                 Life                                                                   Dose   prolonging                                                             (mg/kg)                                                                              rate (%)                                             ______________________________________                                         ##STR17##          5        147                                               ##STR18##          5        180                                               ##STR19##          5        200                                               ##STR20##          5        193                                              ______________________________________                                    

Each side-effect and each solubility to water were tested.

In the tests, severe albuminuria as the indication of kidney toxicitywas found in the control group whereas only slight albuminuria was foundin the groups of the administrations of the compounds of the presentinvention.

The results of the observation of alubuminuria and the solubilities ofthe compounds are shown in Table 4.

The properties of the compound disclosed in the prior art are alsocompared. The improvement of solubilities to water and the reduction ofkidney toxicity of the compound of the present invention are found.

                  TABLE 4                                                         ______________________________________                                                                   Kidney                                                                 Solubility                                                                           toxicity                                                               to water                                                                             albuminuria                                        ______________________________________                                        Inven- tion                                                                           ##STR21##         Δ  ++                                                 ##STR22##         ○ +                                                  ##STR23##         ⊚                                                                       +                                          Refer- ence                                                                           ##STR24##         X        ++++                                               ##STR25##         Δ  ++++                                              Pt(D-glucuro).sub.2 (trans(l)-                                                                   ○ +++                                               1,2-cyclohexanediamine).sup.(2)                                        ______________________________________                                         Note:                                                                         ⊚ highly soluble                                               ○ soluble                                                              Δ soluble by heating insoluble matter at room temperature               X insoluble                                                                   + albuminuria is found for 1 to 2 rabbits in one group of 10 rabbits.         .sup.(1) Sandra J. Meischen. J. Natl. Cancer, Inst. 57 841 (1976)             .sup.(2) Y. Kidani Gann 69 263 (1978)                                    

EXAMPLE 7 Antimicrobial effect

(7-1) Each compound diluted as series of two times dilutions and eachdiluted solution was admixed with Heart infusion agar medium (NipponEiyo Kagaku K.K.) to prepare each plate for culture.

Escherichia coli strain was cultured in Trypto-soy bouillon at 37° C.for 17 hours and one platinum loop of the cultured coliform bacilliusstrain was put on each plate to culture it at 37° C. for 18 hours andeach growth of the strain was observed.

                  TABLE 5                                                         ______________________________________                                        Reduction of coliform bacillius:                                              Dilution times      1        1/2    1/4  1/8                                  ______________________________________                                        Inv.                                                                                ##STR26##         ++       +    +    -                                        ##STR27##         ++       +    +    -                                        ##STR28##         +++      ++   +    +                                        ##STR29##         +++      ++   +    +                                  Ref.                                                                                ##STR30##         ++       +    -    -                                        ##STR31##         ++       +    ± -                                  ______________________________________                                         Note:                                                                         +: growth inhibition of strain                                           

In vitro tests, the antimicrobial effects of the compounds of thepresent invention was found.

(7-2) Since the compounds of the present invention had antimicrobialeffects to coliform bacillius, the infection remedy tests of thecompounds of the present invention were carried out.

Coliform bacillius strain was inoculated to mice by route ofintraperitoneal injection at a rate of 1×10⁸ /mouse. Each compound wasadministered at a dose of 1 mg. to 100 mg./kg. 1 to 3 hours after theinjection by route of intraperitoneal injection or route of oraladministration. During 7 days from the administration, the conditions ofmice were observed to measure survival rates. The survival rates werehigher than 50%.

The fact show that the compounds of the present invention are effectivenot only in vitro tests but also as chemotherapeutic drugs for testinfections.

EXAMPLE 8

Compound No. 1: 50 g.

Lactose: 300 g.

Hydroxypropyl cellulose: 1.5 g.

The components were well mixed and the mixture was tabletted or themixture was kneaded as granulated by passing through a screen of anextrusion type granulation machine and the granule was dried well andtabletted.

EXAMPLE 9

In each vial, 10 mg. of Compound No. 2 was charged in asepsis andmoisture and bacteria were removed in closed condition. Before theadministration, 5 ml. of 5% glucose solution for injection was chargedto prepare an injection.

EXAMPLE 10

In each vial, 50 mg. of Compound No. 4 was charged in asepsis andmoisture and bacteria were removed in closed condition. Before theadministration, 5 ml. of 0.9% physiological saline solution was chargedto prepare an injection.

                  TABLE 6                                                         ______________________________________                                        Table 6-1                                                                     3300 cm.sup.-1 (w)                                                                          2840 cm.sup.-1 (m)                                                                          2620 cm.sup.-1 (m)                                1760 cm.sup.-1 (s)                                                                          1749 cm.sup.-1 (s)                                                                          1590 cm.sup.-1 (w)                                1528 cm.sup.-1 (w)                                                                          1500 cm.sup.-1 (s)                                                                          1430 cm.sup.-1 (m)                                1365 cm.sup.-1 (m)                                                                          1291 cm.sup.-1 (s)                                                                          1225 cm.sup.-1 (s)                                1140 cm.sup.-1 (w)                                                                          1070 cm.sup.-1 (m)                                                                          1040 cm.sup.-1 (m)                                 950 cm.sup.-1 (m)                                                                           878 cm.sup.-1                                                  Table 6-2                                                                     3440 cm.sup.-1 (m)                                                                          3240 cm.sup.-1 (m)                                                                          3100 cm.sup.-1 (m)                                2960 cm.sup.-1 (w)                                                                          1740 cm.sup.-1 (s)                                                                          1570 cm.sup.-1 (m)                                1430 cm.sup.-1 (m)                                                                          1390 cm.sup.-1 (m)                                                                          1300 cm.sup.-1 (s)                                1250 cm.sup.-1 (s)                                                                          1095 cm.sup.-1 (s)                                                                          1015 cm.sup.-1 (m)                                Table 6-3                                                                     3440 cm.sup.-1 (m)                                                                          3280 cm.sup.-1 (m)                                                                          3420 cm.sup.-1 (m)                                3100 cm.sup.-1 (m)                                                                          2960 cm.sup.-1 (w)                                                                          1700 cm.sup.-1 (s)                                1580 cm.sup.-1 (m)                                                                          1430 cm.sup.-1 (m)                                                                          1395 cm.sup.-1 (w)                                1305 cm.sup.-1 (s)                                                                          1260 cm.sup.-1 (s)                                                                          1240 cm.sup.-1 (s)                                1100 cm.sup.-1 (s)                                                                          1020 cm.sup.-1 (m)                                              Table 6-4                                                                     3380 cm.sup.-1 (m)                                                                          1660 cm.sup.-1 (m)                                                                          1600 cm.sup.-1 (s)                                1530 cm.sup.-1 (m)                                                                          1490 cm.sup.-1 (m)                                                                          1410 cm.sup.-1 (m)                                1320 cm.sup.-1 (m)                                                                          1280 cm.sup.-1 (s)                                                                          1170 cm.sup.-1 (s)                                 840 cm.sup.-1 (m)                                                            ______________________________________                                    

We claim:
 1. A platinum compound having a formula ##STR32## wherein Rrepresents hydrogen atom, an alkali metal atom or a lower alkyl group.2. The platinum compound according to claim 1 wherein said lower alkylgroup is selected from the group consisting of methyl, ethyl and propylgroup.
 3. The platinum compound according to claim 1 wherein R is methylgroup.
 4. The platinum compound according to claim 1 wherein R ishydrogen atom.
 5. The platinum compound according to claim 1 wherein Ris sodium atom.
 6. The platinum compound according to claim 1 wherein Ris potassium atom.